<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <script>
      class Person {
        static username = 'jack';
        static say() {
          console.log(this.username);
        }
      }
      class User extends Person {}
      User.say();
      console.dir(User);
      console.dir(User.__proto__ === Person);
    </script>
  </body>
</html>
